I'd rather see one of our sellers respond to your questions but I think this recent blog post from our Product Director might give you some insights about why our for sale pages help you sell more domains:
This blog post which is a tad outdated might give you some insights about why buyers love buying names through our marketplace:
Please let me know if you have any questions.
I just heard from you about undeveloped. There structure seems nice but the design and color theme little awkward. However it's not about their design. i think no one here made sales on undeveloped but i'm going to give it a try and will submit few domains. Let's see their result. Judge you always come up with new amazing things. Thanks.
That's a lot of domains with only .01% inquiries and no sales.
Why not create your own market place for these domains? You keep your customers with you and upsell your own.
A small work for a long term results.